1. Field of Endeavor
The present invention relates to DNA sequences and more particularly to constructing very long DNA sequences.
2. State of Technology
United States Patent Application No. 2003/0068643 by Thomas M. Brennan and Herbert L. Heyneker for methods and compositions for economically synthesizing and assembling long DNA sequences published Apr. 10, 2003 provides the following State of Technology information, “The advent of rapid sequencing technology has created large databases of DNA sequences containing useful genetic information. The remaining challenges are to find out what these genes really do, how they interact to regulate the whole organism, and ultimately how they may be manipulated to find utility in gene therapy, protein therapy, and diagnosis. The elucidation of the function of genes requires not only the knowledge of the wild type sequences, but also the availability of sequences containing designed variations in order to further the understanding of the roles various genes play in health and diseases. Mutagenesis is routinely conducted in the laboratory to create random or directed libraries of interesting sequence variations. However the ability to manipulate large segments of DNA to perform experiments on the functional effects of changes in DNA sequences has been limited by the enzymes available and their associated costs. For example, the researcher cannot easily control the specific addition or deletion of certain regions or sequences of DNA via traditional mutagenesis methods, and must resort to the selection of interesting DNA sequences from libraries containing genetic variations.
It would be most useful if a researcher could systematically synthesize large regions of DNA to determine the effect of differences in sequences upon the function of such regions. However, DNA synthesis using traditional methods is impractical because of the declining overall yield. For example, even with a yield of 99.5% per step in the phosphoramidite method of DNA synthesis, the total yield of a full-length sequence of 500 base pairs long would be less than 1%. Similarly, if one were to synthesize overlapping strands of, for example, an adenovirus useful as a gene therapy vector, the 50-70 kilobases of synthetic DNA required, even at a recent low price of approximately $1.00 per base, would cost over $50,000 per full sequence, far too expensive to be practical when compared with the enzymatic synthesis of DNA using PCR technology.”
U.S. Pat. No. 6,375,903 issued Apr. 23, 2002 to Francesco Cerrina et al for a method and apparatus for synthesis of arrays of DNA probes provides the following State of Technology information, “The sequencing of deoxyribonucleic acid (DNA) is a fundamental tool of modern biology and is conventionally carried out in various ways, commonly by processes which separate DNA segments by electrophoresis . . . . One such alternative approach, utilizing an array of oligonucleotide probes synthesized by photolithographic techniques is described in Pease, et al., “Light-Generated Oligonucleotide Arrays for Rapid DNA Sequence Analysis,” Proc. Natl. Acad. Sci. USA, Vol. 91, pp. 5022-5026, May 1994.”
International Patent Application WO 02/095073 by Peter J. Belshaw et al published Nov. 28, 2002 for a method for the synthesis of DNA sequences provides the following State of Technology information, “Using the techniques of recombinant DNA chemistry, it is now common for DNA sequences to be replicated and amplified from nature and for those sequences to then be disassembled into component parts which are then recombined or reassembled into new DNA sequences. While it is now both possible and common for short DNA sequences, referred to as oligonucleotides, to be directly synthesized from individual nucleosides, it has been thought to be generally impractical to directly construct large segments or assemblies of DNA sequences larger than about 400 base pairs. As a consequence, larger segments of DNA are generally constructed from component parts and segments which can be purchased, cloned or synthesized individually and then assembled into the DNA molecule desired.”